Ba2TeO: A new layered oxytelluride

• Single crystal synthesis of a new layered oxytelluride, Ba2TeO.
• The structure features inverse PbO-type BaO layers and NaCl-type BaTe layers.
• Optical absorbance show Ba2TeO to be a semiconductor with a 2.93 eV gap.
• Density of states indicate a small hybridization between Te 5p and Ba 5d states.
• The BaTe (BaO) layers dominate the heat capacity at low (high) temperatures.

Single crystals of the new semiconducting oxytelluride phase, Ba2TeO, were synthesized from barium oxide powder and elemental tellurium in a molten barium metal flux. Ba2TeO crystallizes in tetragonal symmetry with space group P4/nmm (#129), a=5.0337(1) Å, c=9.9437(4) Å, Z=2. The crystals were characterized by single crystal x-ray diffraction, heat capacity and optical measurements. The optical measurements along with electronic band structure calculations indicate semiconductor behavior with a band gap of 2.93 eV. Resistivity measurements show that Ba2TeO is highly insulating.

Starting from a simple stacking of rocksalt layers, the final structure of Ba2TeO can be obtained by accommodation of structural strain via atom displacements. Density of states calculations and optical absorbance measurements show that Ba2TeO has a band gap of 2.93 eV, indicative of semiconductor behavior. Figure optionsDownload as PowerPoint slide